Two patients had acute spontaneous dissection of both internal carotid arteries and of one or both vertebral arteries. One had angiographic signs suggestive of fibro-muscular dysplasia and both were on oral contraceptives. They were treated with high dose heparin and made a good clinical recovery. A digital intravenous angiography performed two to three months later showed a complete recanalization of arteries involved. These patients are similar to those reported as "idiopathic regressing arteriopathy" and "reversible angiopathy" which probably correspond to the same entity.